TRANSGENIC AND CHIMERIC MOUSE CORE: Director-N. Cooke The Transgenic and Chimeric Mouse Core Facility (TCMF) of the University of Pennsylvania has been in operation since February 1992 under the continuous co-direction of Dr. Nancy Cooke and Dr. Stephen Liebhaber and under the day-to-day technical direction of Dr. Jean Richa. The initial components of the TCMF were assembled from financial contributions of the School of Medicine and resources from the laboratories of Drs. Cooke and Liebhaber in 1989 with subsequent phased expansions in facilities, capabilities, personnel, and services. Over the past five years the Core has generated a wide range of transgenic and gene-targeted mouse lines that have proven to be powerful tools for the study of the molecular biology and physiology of Type I and Type II diabetes, obesity, and developmental and mechanistic bases for a wide variety of other disorders of endocrinology and metabolism. The Core laboratory is located in a pathogen-free microbiologic barrier facility in the basement of the Clinical Research Building. A primary function of the TCMF is to provide a centralized laboratory that will generate infectionfree strains of mice carrying transgenes or targeted genetic alterations of specific interest to individual projects in the DERC. The centralization of these technically demanding procedures in the Core laboratory results in enhanced efficiency and significant cost reduction for each project. During the current project period the TCMF has grown significantly in service offerings and its facilities have been improved and expanded. A major increase in the throughput potential of the Core has been achieved by the doubling in the size of the Core microinjection laboratory, funded by the School of Medicine. This expansion has doubled the capacity in line with the continuing increase in demand for services. In addition, the Core is now finalizing a new Cryopreservation Facility for the long-term storage of embryos and sperm. This addition to the Core will be opening in the summer of 2006. This newly configured, secure facility is off-site from the main Core laboratory, and has been established by funds from the School of Medicine. Additional services that have been established during the current funding period include sperm cyropreservation, intracytoplasmic sperm injection (ICSI), DNA diagnostics, and integration with the School of Medicine gene knock-out service. These services have substantially increased the utility of the Core to Center members. The Core will continue to maintain the highest level of quality service and will continue to acquire new techniques and expertise to maintain services at a 'state-of-the-art'level.